We had a batch of 7 recently, one didn't seem to be able to get out after pipping, my husband helped by zipping the shell, the little one finished the job and popped out, 3 never pipped, when we checked the eggs it seemed that one was not fully ready, yellow liquid inside egg, 2 seemed to be fully developed but they seemed stuck. I hated to see 2 perfectly formed chicks not make it.
Now we have another batch of 7, 4 hatched yesterday, 2 have no signs of pipping, 1 has pipped and is alive and chirping, my husband zipped a little bit of the shell and baby chick just popped out. We will have to see how this little one does. We are struggling with the idea of pipping the 2 unpipped eggs, no harm if they aren't alive anyway, but don't want to cause problems if they are.... anyone else ever pipped eggs with success??